The invention relates to crimping tools, particularly manually operated crimping tools. Specifically the invention relates to a cam roller brake for such crimping tools.
Manually operated crimping tools for affixing connectors to electrical wires utilize a cam actuated toggle mechanism for opening and closing crimping jaws which establish the connection. It is desirable to manipulate the toggle mechanism in distinct crimping cycles measured by one full rotation of the actuating cam. That is, the cam should at the end of each cycle return to a home or start position with the crimping jaws at maximum opening. Because of the very substantial forces developed between the cam and toggle mechanism there is a tendency for the cam to rotate past the home or start position when unloading a crimp and come to rest at a point in the next crimp cycle. This problem is described in U.S. Pat. No. 3,101,017 wherein the jaws and toggle when compressed to their closed or crimp position store energy in the manner of a spring. When unloading a crimp the actuating cam releases the cam follower, the toggle and jaws assembly, and they release their stored energy driving the follower against the cam. The result is a tendency to drive the cam past its home or start position into the next crimping cycle.
To overcome this tendency, the crimping tool of the '017 patent utilizes a friction braking mechanism consisting of a leather lined spring steel band to control rotation of the cam by counteracting the force exerted by the cam roller on the cam when the crimp is unloaded and the cam begins its return to the home position. The friction band brake mechanism is limited to smaller jaws resulting in a limitation in the range of connectors handled by the crimping tool. It has been determined that the existing brake mechanism is not effective with larger crimping jaws which are necessary to deal with a wider range of connectors.
The higher crimping forces associated with larger crimping tools accelerate the cam causing it to spin very rapidly when a crimp is unloaded so that the cam is positioned well into the next crimp cycle where the jaws are partially closed. The problem is amplified considerably if the crimping tool has been immersed in oil because the friction brake band is virtually useless when lubricated. Under these circumstances the operator cannot remove the tool from the crimp connection. The tool must then be disassembled which is an unacceptable situation.